You can't load palettes in Paint. Look at some other tools such as PaintShop Pro (retail), PhotoShop (retail but expensive) or a tool with a rather low learning curve such as LViewPro (available via shareware). Do a google search. I believe LViewPro does support dithering (reducing # of colors of) an image down to a predefined palette (A palette is nothing more than a 1x1 pixel bitmap with a 256 color palette.

To create a palette, you can use CCFTools to decompile the CCF, pick a bitmap used for the Macro Template, resize it to 1x1 and use if for a palette.

Lyndel